Sudden infant death syndrome, commonly known as SIDS, refers to the sudden unexplained death of an apparently healthy infant under the age of one. It is the most common cause of death in infants between the ages of one month and one year in developed countries. The risk in the United States is .57 per 1000 births. Families that have lost one child from SIDS have a higher risk of recurrence.
Interesting facts about SIDS:
- More common in boys than girls (60:40 ratio)
- Peaks between 2 to 4 months and generally occurs before 6 months of age
- Blacks, American Indians, and Native Alaskans have 2 to 7 times the risk over the national average
- Japan and Netherlands have the lowest incidence; New Zealand has the highest; USA and UK are intermediate risk
- Risk is declining worldwide
- Premature infants with low birth weights have four times the risk of SIDS compared to full term infants.
Risk factors for SIDS
- Sleep position
Numerous studies have shown that the supine position reduces the risk of SIDS by a factor of 20. Both side position and prone position have similar risks and should be avoided.
- Maternal smoking
Prenatal and postnatal smoking both increase the risk of SIDS. Findings show that smoking decreases lung volume and heart rates in the infant. Nicotine also causes detrimental effects on the infants ability to respond to low oxygen levels.
- Soft bedding and accessories
Pillows, quilts, comforters, and porous mattresses all increase risk of SIDS. Infants should not sleep on a couch or armchair. The American Academy of Pediatrics recommends that infants sleep on a firm surface without accessories.
- Warm room temperatures
Overheating of infants with multiple blankets, clothing layers, in a warm room increases the risk of SIDS, especially when infants are placed in the prone position.
- Bed sharing
Co-sleeping increases SIDS risk especially for infants under 11 weeks of age, when the mother smokes, drinks, or is overtired and the infant shares the bed for the entire night. Half the infants who die of SIDS in the United States co-share beds. The ideal environment is in a crib or bassinet separate but near the mother’s bed.
Risk of SIDS is reduced with use of pacifiers. These infants have been found to have improved ability to breathe with their mouth and have less of a chance of oropharyngeal obstruction.
What Causes SIDS?
The cause of SIDS is due to three important factors occurring coincidentally
- Vulnerable infant—the theory is that children that succumb to SIDS have abnormalities in their arousal system and are unable to compensate for low oxygen levels. This ability is controlled by certain parts of the brainstem and hypothalamus. There are probably genetic differences that involve serotonin transport activity in the brain and the autonomic nervous system.
- Critical developmental period—the child must be within the first year of life
- Exogenous source—an outside stress like prone sleeping or nicotine exposure.
What Are Some Misconceptions About SIDS?
- Apnea monitor—There is no evidence that they are useful in preventing SIDS
- Immunizations—There is no evidence that immunizations increase the risk of SIDS
- Breast feeding—there is no evidence that it protects an infant from SIDS
SIDS is due to an interaction between genetic and environmental factors. Teaching parents safe sleeping practices for their infants is essential in reducing the risk of this disease. In particular, sleeping children on their backs, avoiding tobacco and alcohol use, avoid overheating the infant, sleeping children on a firm mattress in a separate bed without accessories , and use of a pacifier can reduce the risk of this problem.